Video piracy is a common problem. Unauthorized copies of videos, such as movies and television shows, are often made and distributed without compensation to the owner of the video. This can cost copyright owners and content providers significant amounts of money.
Many copy protection and/or digital rights management schemes have been developed to prevent digitally distributed videos from being copied bit for bit without authorization. For example, digital video is often encoded and encrypted such that only hardware with access to a particular decryption key can decrypt and play back the video.
However, even if copy protection and/or digital rights management make it difficult to copy a digital video directly from a source file, these protection schemes do not protect against someone using a video camera to record otherwise authorized playback of a video from a screen. This is sometimes referred to as the “analog hole,” although digital video cameras are also used to capture video playback off screens. For example, while copy protection might prevent a video pirate from ripping video straight from a DVD, the pirate can simply play the DVD on a DVD player and capture the video in real time with a video camera as it is displayed on a television screen. While the result may not be a perfect digital copy, the quality may still be good enough to distribute.
Solutions to the “analog hole” have included inserting high frequency artifact frames into a source video. However, camcorders can be set to a matching sampling frequency in order to filter out the artifact frames and capture only the frames of the main content.
Unauthorized viewing can also be a problem in the context of pay-per-view events. Content providers, such as cable companies, sometimes offer movies, shows, or special events like boxing matches on an on demand basis for a fee. Purchasers gain access to the pay-per-view event, and can display it on their television. However, in some cases the content provider may wish to limit how many people are authorized to gather around the television and watch the event, even when the event has been purchased legally.